We propose to develop a re-amplifiable tiling path resource for the entire euchromatic Drosophila genome. This resource will be used for the production of genomic DNA microarrays to be distributed to the community at cost of printing. These arrays can be used for DNA-protein interaction mapping, comprehensive expression profiling, replication origin mapping, comparative genomic hybridization, physical mapping of deletions, and other applications. Protocols for use with this resource will be developed and disseminated, and a database and data management service will be established for use by users of the whole genome tiling path microarrays. This resource will be distributed to a wide community of researchers through the Drosophila Genomics Resource Center. Additionally, a strategy is proposed to use a newly developed, well-addressable system of re-amplifiable tags. The entire genome in the form of lkb PCR products will be distributable to individual labs in four 384 well plates. A researcher will be able to amplify any or all of the genome tiling fragments using pairs of 20 unique primers. This feature of the proposed resource would enable comprehensive RNAi screens, rapid cloning of regulatory sequences, and potentially many other applications.